How do birds handle toxic food in the wild

[ramsabi]

I am starting this thread as a spin-off from the "What do you feel is Safe/ Unsafe to feed Parrots" thread.

 

2 reasons why I am starting this thread:

 

1. That thread has as its topic safe and unsafe foods with excellent contributions and I do not want it to digress.

 

2. This question has always bothered me.

 

I am assuming that most if not all of the food that we give our greys are not their "natural foods" in the sense that they do not have access to these in the wild - e.g. avocado.

 

If avocado had been present in their wild habitat, would they have learnt to avoid it?

 

Also danmcq had an interesting contribution in that thread:

 

<snip> Yes, birds in the wild will eat poisonous plants an items. What they have going for them, that our house birds do not, is the daily ingestion of "Clay" that coats their digestive system and absorbs these poisons and basically lets the "healthy" portion of the food item get digested. <snip>

 

This sounded very interesting and I googled it:

 

Wikipedia had the following passage in an article on Macaws and clay licks:

 

Macaws eat a variety of foods including fruits, palm fruits, nuts, seeds, leaves, flowers, and stems. Wild species may forage widely, over 100 km for some of the larger species such as Ara araurana (blue & yellow macaw) and Ara ambiguus (great green macaw), in search of seasonally available foods. Some foods eaten by macaws in the wild contain toxic or caustic substances which they are able to digest. To date, there are no studies that directly show how these substances are tolerated. Though it has been suggested by some that parrots and macaws in the Amazon basin eat clay from exposed river banks in order to neutralize these toxins, recent studies show that these clays do not have the ability to absorb toxins. Rather, these clays are eaten for their sodium content. Donald Brightsmith, the principal investigator of the Tambopata Macaw Project, located at the Tambopata Research Center (TRC) in Peru, has studied the clay eating behavior of parrots at clay licks in Peru. He and fellow investigators found that the soils macaws choose to consume at the clay licks do not have higher levels of cation exchange capacity (ability to adsorb toxins) than that of unused areas of the clay licks [7] and thus the parrots could not be using the clay to neutralize ingested food toxins. Rather, the macaws and other bird and animal species prefer clays with higher levels of sodium [8] [1]. This makes sense since sodium is a vital element that is scarce in environments >100 kilometers from the ocean On the biogeography of salt limitation. Salt-enriched (NaCl) oceanic aerosols are the main source of environmental sodium near coasts. Environmental sodium decreases drastically farther inland and patchy distributions of sodium leaching from rocks becomes the primary source of sodium in the environment. Exposed sodium-rich deposits in river banks become magnates for sodium-deprived birds and animals.

Additionally, macaws found in regions such as Mexico and Central America have never been observed visiting clay licks or eating soil. This makes sense in light of the theory that sodium is the attractant for geophagy. Most regions of Mexico and all of Central America are within 100 km of a coast and thus receive sodium via ocean aerosols.

As well, clay-eating behavior by macaws is not seen outside the Amazon region even though macaws in these areas consume toxic foods such as the seeds of Hura crepitans, or sandbox tree, which have toxic sap Sandbox tree. One unpublished theory is that these birds also consume other plants containing detoxifying agents such as tannins that neutralize the toxins.

 

So is the "eating clay to neutralise toxins" a myth without scientific basis or is the above article erroneous?

 

Let me hasten to add that my first assessment of almost any info on the net including Wikipedia is made on a sceptical basis unless I find corroboratory evidence.

 

But that question is not the main purpose of this post.

 

I would be very interested to know if birds and in fact all animals "learn" to avoid toxic foods in the wild or whether they do eat them and suffer the consequences.

 

Post edited by: ramsabi, at: 2010/02/10 06:32

 

Post edited by: ramsabi, at: 2010/02/10 06:34<br><br>Post edited by: ramsabi, at: 2010/02/10 06:36

[Jayd]

Wonderful post, I typed "clay for my parrot" on the net, here's what I got!!! [1 PAGE]

http://www.smh.com.au/articles/2002/04/06/

1017206270310.html

http://www.inkanatura.com/macawclaylicks.asphttp://www.shirleys-wellness-cafe.com/clay.htm

http://www.24parrot.com/Natural-Clay-Mineral-Block-for-Parrots-

A starter...:)Jay

[danmcq]

There have been studies performed on the clay Parrots around the world, not just in the Amazon that have in fact resulted in the data that clay does remove toxins:

 

James D. Gilardi1, 2 , Sean S. Duffey2, Charles A. Munn3 and Lisa A. Tell4

 

(1) Section of Evolution and Ecology, University of California, Davis, California, 95616.

(2) Oceanic Society, Fort Mason Center, San Francisco, California, 95616

(3) Wildlife Conservation Society, 2300 Southern Boulevard, Bronx, New York, 10460

(4) School of Veterinary Medicine, University of California, Davis, California, 95616

 

 

Abstract-

 

This study tests hypotheses on the biochemical functions of geophagy in parrots: mechanical enhancement of digestion, acid buffering capacity, mineral supplementation, adsorption of dietary toxins, and gastrointestinal cytoprotection. Parrots showed clear preferences for specific soil horizons.

 

Comparisons of preferred and nonpreferred soils from several sites suggest that soils have little ability to enhance grinding and no measurable ability to buffer gastric pH.

 

Soils offered insignificant mineral supplementation since most minerals occurred at similar levels in samples regardless of preference, and the minerals were generally more plentiful in the birds' diets. Sodium was available in moderate levels at some sites (>1000 ppm), but was well below sodium detection thresholds of parrots.

 

X-ray diffraction, cation exchange capacity, and in vitro adsorptive trials showed that the preferred soils are capable of exchanging substantial quantities of cations and are capable of adsorbing low-molecular-weight secondary compounds.

 

In captive Amazona parrots, orally administered clay reduced the bioavailability of the alkaloid quinidine by roughly 60%, demonstrating that in vivo adsorption of potentially toxic compounds may be a biologically important function of geophagy. Labeled clay remained in the lower gastrointestinal tract of captive parrots for >12 hr, which along with high adsorptive capacities, further suggests a potential role in protecting the gastrointestinal lining from various biological and chemical insults. Detoxification and cytoprotection are the most likely functions of geophagy for parrots and herbivores with similar ecologies.

 

Given the variety of chemically defended seeds consumed by these herbivores, geophagy likely protects consumers from dietary toxins, allowing increased diet breadth and/or enhancing digestibility.

Parrot - macaw - geophagy - clay - mineral - detoxification - secondary compounds - dietary ecology - cytoprotection

[ramsabi]

So as usual there seems to be no scientific consensus

[Greywings]

Great thread subject very interesting but nothing that answers all involved in this question. So I will add my equally incomplete two cents. Since most Parrots are sight feeders it would seem safe to surmise that they learn what is safe from watching their flock mates, as they watch what we eat in our homes.<br><br>Post edited by: Greywings, at: 2010/02/10 18:42

[ramsabi]

Hi Jayd, thanks for the links. I read the material in the sites.

 

The first one is a newspaper article. But some statements have been attributed to the Director of the World Parrot Trust. I am a member of the WPT and coincidentally I have posted the "clay question" to the experts forum resource available there.

 

The second one is a tour promotion site for Peru. The article is By Charles A. Munn, Ph.D., Chairman of the Board, Tropical Nature (a nonprofit nature conservation group---www.tropicalnature.org) and he says:

 

....The clay appears to detoxify the nasty poisons in their diets of seeds of rainforest trees and vines.

 

The key word is "appears" !!

 

The fourth one appears to be a commercial site and therefore with suspect credentials. Similar theories have been used for bitter almonds, Vitamin B17 and laetrile as possible cancer cures.

 

The fifth one is also a commercial site and the product description does not claim anti-toxic effects. It says

 

This block provides the minerals and trace elements naturally found on the banks of the Amazon river in Brazil, Parrots are often seen there eating the mineral rich clay.

 

I have googled '"Geophagy" in African Greys' and it returned ONLY 475 hits and most of the info is again speculation or promotion.

 

The following link has some good info:

 

http://www.harrisonsbirdfoods.com/stanford-fellowship.pdf

[dblhelix]

It may be very difficult to find many good scientific papers on these topics. Its just not likely to be something really well studied, funded etc. Not much demand. I am sure there are some and it certainly is an interesting topic to many of us! My thoughts are that of course wild birds (as all animals) get exposed to toxic substances and many must suffer the consequences (eg die). Much of their protection likely comes through the learned route. They are long lived animals and as such have a great capacity to learn through life experiences and the habits/experiences of others. It also seems possible that the natural habitat, foods, environment etc may provide some additional protection that our "pets" would not benefit from (living in flocks with mature birds that have managed to survive is probably a huge benefit). On the other hand, our pets are provided protection from predators and other dangerous things that wild animals are not...interesting post. B)<br><br>Post edited by: dblhelix, at: 2010/02/10 21:26

[danmcq]

I believe the abstract from the scientific study is the best and most conclusive study found to date.

 

It did indeed find the clay absorbed toxins.....

 

The others are not based on actual in-depth studies as the one performed by UC Davis.

 

A side note - Harrisons pellets and some other manufacturers also provide clay in there pellets based upon data they have that indicates it removes toxins.....

[Jayd]

:unsure: I'm surly getting senile in my old age. I picked 4 sites at random with out even reading to show there was info available on the net.:whistle: Sorry, I should have explained...Jay

[Jayd]

This link is from Jillybeanz, she posted it in the Amazon Room, which I love, and I would like to share it here. Jay:)

Thank you Jillybeanz...

http://www.youtube.com/watch?v=ZZRtPNSro9g